Ubuntu’s own desktop module is called “Unity” and it was first introduced with the 11.04 Natty Narwhal release. It comes in two versions.
One is called Unity 3D (default version) and the other is known as Unity 2D. Unity 3D is somewhat the “eye candy version” of Ubuntu as it relies on Compiz (advanced Compositing window manager) for drawing 3D looking graphics, transparency or minimizing/maximizing effects etc.
But those pretty graphics require OpenGL rendering (3D graphics “drawing” library just like Microsoft’s own Direct X), unless you have a reasonably powerful GPU the default Unity 3D desktop might struggle to run properly on your computer.
In those occasions, if Ubuntu decided that your current hardware does not meet the minimum requirements of Compiz, then it’ll automatically switch to the Unity 2D version. Unlike with its 3D cousin :D, Unity 2D does not need a lot of your system resources.
Now in both these versions you get the almost the same looking desktop, including the ‘Application Launcher’.
But now and then, there could be times where this “application launcher” gets stuck. Sometimes it might not function at all or other times it would function, partially. For instance, this one time as you can see with the first screenshot, application launcher in my Unity 2D desktop got stuck (kinda) and the “Dash” icon too got Grey instead of the default Black color and stopped working.
If you encounter something like this, then other than log-out and re-login to fix that, there’s a simple command that you can use to manually restart this Application Launcher.
For that if you cannot open a Terminal via the Application launcher. If it doesn’t work, then press “Ctrl” + “Alt” + “t” keyboard shortcut and enter the below command.
Again please remember this only works in Unity 2d desktop only.
Yep that should do it!.
After entering this command wait for few seconds. First the “troublesome” launcher should disappear and within few seconds a new application launcher should be launched automatically!. And most of the time it should contain your last opened apps etc.
But please remember that I cannot guaranteed that this will work all the time, but hey!, it’s better than nothing ;-). Good luck.